Improving frictional properties in lubricant compositions has been an objective of the industry. Friction between two surfaces will increase the power required to effect movement, and where the movement is an integral part of an energy conversion system, it is most desirable to effect lubrication in a manner that will minimize this friction. By minimizing friction in a lubricant system, fuel economy and energy efficiency are maximized. Friction modifiers have been used to promote such friction-reducing properties in lubricant systems.
A variety of friction modifiers are known in the art and include both ash and ashless modifiers. Recent emission concerns have resulted in a preference for ashless friction modifiers, such as fatty acid esters and amides. While efficacious, fatty acids tend to have a low solubility in base oil, decompose over time, and increase the acidity of the formulation.
Currently, there is a need for ashless additives that effectively reduce the friction coefficient of oil-based lubricants, but have improved solubility in base oil and/or sustained performance over time.